This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The purposes of the research are to understand ion motion in modified FTMS traps, to construct traps guided by the theoretical considerations, and to test the effectiveness of the electrically compensated cell to study high-mass ions generated by MALDI. The goal of this core research project is to improve the detection for biomolecule ions with mass-to-charge ratios greater than a few thousand by making changes to the electrical properties of the trap rather than by increasing the magnetic field strength. We suggest that the instrumentation will not only be of interest for mid-sized proteins but also for peptides in proteomics applications.